Course corrector



`PJM, KRAMER. COURSE CORRECTOR. APPLICATION FILED AUGJZ. IBIS.

5L/ ATTORNEYS.

' and an indicating disk or dial, the -latter over.

UNITED STATES lPA'IENT OFFICE.

FRED M. KRAMER, 0F SAN FRANCISCO, CALIFORNIA.

Application led August 12, 1919. Serial No.

compass error and the correction of a given course.

An object o'f the invention is to provide a device of the character 'described which will course to be made good and the course to be steered in order to allow for the compass error and make good the desired or given course, thus eliminating all uncertainty as to the correct manner of applying the com# pass error and avoiding mistakes in steering.

Another object is to provide a course corrector o the character described which is relatively small, simple as to construction, inexpensive and capable of being so placed with relation to the compass that the navigator may be guided by the indications made visible by the cor-rector'and act accordingly without liability of error in the application of the correction tothe compass.

The invention possesses'other objects and features of advantage, some of whlch, with the foregoing, will be set forth in the following description of the preferred form of my invention which is illustrated in the drawings accompanying and-forming part of the specification. It is to be understood 'that I do not limit myself to the showing made by the said drawings and description, as I may adopt variations of the preferred form within the scope of my invention as set forth in the claims. Referring to the drawings: Figure 1 is a top plan view of my invention.

Figure 2 is a vertical sectional view taken on line 2-2 of Figure 1.

In carrying out my invention I preferably employ a at envelope or casing of some light non-magnetic material andl within the envelope I rotatably mount a compass card the former. Both of these elements have a com/mon pivot and eachextends out of the casing or envelope so that it may be turned Specification of Letters Patent.

the envelope.

coUnsE coimnc'roa.

Patented Feb. 7, 1922.

by the fingers of the user. One edge of the dlal 1s straight and acts as a pointer or indicator with relation to the compass card so that by reading the card directly in line with said edge the direction of the course to be steered may be determined.

A strip bearing a deviation scale is slidably mounted within the envelope and provlded with means for effecting the reciprocation of the slide from the exterior ofl 'lhe envelope is preferably opaque but is provided with'segmental transparent portions arranged arcuately and concentric with the axis of the card so that the calibrations on the card may be read. Com# pass error scales are printed along-'the outer edges of these portions and these scales are calibrated in degrees. On the inner edges of the transparent portions are provided error scales calibrated in points The envelope is provided with another transparent portion over the deviation scale and along one edgeof this portion a combined compass error and variation scale is provided.

' Knowing the deviation and variation, the total or compass error may be readily determined by proper manipulation of the scale strip with relation to the eror scale with on the error scale. By properly manlpulatsoA ing the compass and card and disk or dial with relation to the scales, the course to be steered will be indicated by the dial and the course which is to be made good is also shown by a black line extending across the transparent portions over the center of the compass card. The reading of the card under the line is the direction of the course to be made good. Thus I may correct the compass course to a magnetic or true course or I may correct the true or magnetic course to determine the compass course, all so that the error or correction may be visualized and the relative directions of the course shown so that mistakes in application of the error may be'avoided.

My. invention comprises preferably a nonmagnetic body or casing 1 in the form of an envelope which consists of an upper, preferably opaque, sheet 2 and a bottom sheet 3. The upper sheet is folded at its edges as at 4 so as to overlap the edges of the sheet 3 and suitable fastening elements 5 are lnserted through the overlapped portions to hold tht sheets together.

There are provided,y segmental transparent i portions 6 and v7 arranged opposite to one viation scales 9 and' 10 both calibrated in Vdegrees and concentric with the scales 8.

, pin being disposed between the segmental transparent portions 6 and 7 and inserted The scale 9 is for easterly compass errors" or deviation, the scale 10 for westerly compass errors or deviation and the scales ma be thus designated as shown in the drawings.

An ordinary compass card 11 is rotatably mounted on a pin 12 within the envelope, the

through the sheets'2 and 3 of the envelope. This card is. so arranged with. relation to the portions 6 and 7 that substantially half of the card is visible, that is, two opposite quadrants of the card are preferably shown and the axis of the cardis concentric with the curved inner and outerl edges ot the scales 8, 9 and 10'so that the calibrations on' the c'ard may be brought to alinement with the scale calibrations. The card eX tends past the upper edgeor the envelope through a slot 13 therein so that it may be turned as desired. .p

A line 14, preferably black, is drawn across each segmental transparent portion and extends'across and over the center of the card radial `vthereto so that any calibra- -tion on the card may be brought to register' with the line. Thisline may be termed the true or magnetic course indicating' line.

. An indicating member 15 of transparent material is mounted for rotation on the pin 12 -over the compass and is substantially semi-circular, the straight or indicating and pointing edge 16 thereof intersecting and being radial to the axis of the card so that' it may be brought to ',alinement with calibrationson the card and those of the scales 8, 9 and 10. This edge is the compass course indicating edge and is preferably so marked as shown'in the drawings. f

yThe lower edge of the envelope is slotted and cut away as at 17 and the curved edge .18 of the vmember 15 extends through the 'means comprises a slide strip 19 movable slot into the cut away ortion so as to provide forthe turning o the member.

Mechanical calculating means is provided for computmg the compass error and this back and forth within the envelope under 8f,

`transparexl'teiportion` 20-in the upper'sheet 2.

of said en o Operating buttons 21 and to the end portions of the strlp and workin slots 23 and 24 formed in the sheet 2. These 'buttons provide .for the moving of the strip back and forth. The

' .strip bears'a scale calibratedin degrees from 0 at middle of the' strip to `60 or more 'known to be 10 W.

'found t0 be 4'l E.'

at each end, that is, the calibrations read 11 to from each side of the 0 mark an the left side 25 lis for easterly deviation whereas the rightjside 26 is .for westerly deviation, each side being so marked.

Along the upper edge of the transparent .portion 20 a combined variation and compass error scale is provided for cooperation with the scale on the strip 19. This scale is divided identically with the scale on the strip, the right'side 27 thereof being for westerly errors and westerly variations, and the left side 28 thereofbeing for easterly compass errors and the sides are thus marked.

Assuming that a navigatorwishes to make good a course due West, 270 angular measure and the deviation is known to be 5 east, the variation according to the chart being 20 east, the slide strip 19 is properly moved by the buttons 21 and 22 so as to bring the 0 mark under the 20 variation mark of the easterly variation, Aside 28 of the variation scale. The total, error is then ,shown above the 5 mark on/ the variation scale`'and is found to -bei 25 veast. If the compass showed a 5 westerly deviation the total error would be oundto be 15 east.

, Having thus quickly and accurately found the compass errors which is the algebraic sum of the deviation and variation errors, the compass card isnext turned' so as to bring the 270 or due west mark to lie 4directly under and in line with the true course line- 14 preferably on-the transparent serve asa guide to the navigator in steering f the-ship. 1 y

Withthe course to be made good, due west or 270, deviation 5 E. varlation 20 'E.

compass error 25 E. the course to be steered or compass course is found to be approximately 2i points south of W. or S. W. by W.

`W. or by angular measure 245 degrees.

.i Now if the course to be madegood is S. or

180 the compass card south mark is brought .opposite to the true course line 14' oli-the.

vtransparent portion' 7. The deviation and the variation is The deviation scaleto d bring the 0 mark thereon the. 4. E. variation mark-on tlieeastlsde 28 of said variation scale'.

10 W. mark on the west side 26 ofthe deviation scale on the strip it is found opposite to the 6 mark on the west side 27 of the compass error and variation scale and the total compass error is the algebraic sum as shown, viz. 6 lV. The member 15 is then turned to bring the edge 16 on the rightv side thereof in ne with the 6 mark on the west compass error scale l0. By then reading the compass along this edge of the disk the course to be steered may be determined. In this casethis course is found to be approximately if point west of South, or S. lV.. or 1 86 degrees angular measure.

Summing up the foregoing, it may be said that the invention lies in the provision of means for compelling a correct application of the compass error to make good the desired course. The computation of the totalcompass error is a simple matter and mis-v takes do not happen with ordinary care. It is in the application of the error to make good the true course that mistakes occur; that is, an easterly correction is made for a westerly error and a westerly correction for an easterly error. My device compels ach'o-ice of visible, material elements, thus requiringl a specific selection of the easterly or westerly side of the device for indicating the course. The easterly error is applicable on one side of the device and the westerly error on the other. They cannot be superposed or confused, and knowing lthe error, one cannot misapply it without ignoring the prominent indicia..

It will be seen that the present device embodies a compass card that is co-ordinate to duplex segments of degree arcs, having a center common with the center of the cornpass card ;'the degree segments consisting essentially of indicating means with respect to which there may be adjusted an index member having respective index portions for each of the indicia 9 and 10 so that one portion ofthe index member is utilized in making correction for easterly courses while the other is separately usable for westerly correction. Again by the present device the corrected course may be found bya minimum move.

ment of the index member 15 inasmuch as it is provided with radially opposite index edges 16 and for the purpose of reducing or obviating error the device includes a cover member having windows through which are exposed adjacent portions of the compass card and through which windows onl one @or the other of the index portions of t e index member 15 can be e ectively presented inasmuch as the indicia arcs spring from a common base or` zero line passing through the common center of the movable members. The windowarea of the cover 2 is such that as one of the index edges or portions 16 of the index member moves beyond a predetermined point in the setting of the device l rotative about the pivot and having its de! gree calibrations contiguous to the outer edges of the windows, east and west degree indicia extending from diametrically opposite zero points around the outer edges of the windows and (zo-ordinate with the compass degree scale, and a course index member interposed between the card and the mounting and having opposite indices to be set in selective relation to the respective indicia and sho-w, on the compass card, the compass course.

2. A device of the character described, comprising a mounting having diametrically opposite segmental windows, a pivot at the center of thearcs, a compass card, rotative about the pivot and having its degree calibrations contiguous to the outer edges of the windows, east and west degree indicia extending from diametrically opposite zero points around the outer edges of the windows and co-ordinate with the compass degree scale, and a course index member interposed between the card and the mounting and having opposite indices to be set in selective relation to the respective indicia and show, on the compass card, the compass course and arcuate scales at the inner edges ofthe windows for showing the corrected course in points 3. A device of' the character described comprising a top member with opposite windows, a pivot about which are scribed angular east and west scales at the outer edges of the windows, a courseindex memberon the ivot and below the windows, and having ra ial indices to be set at respective scales at the windows, and acompass card turnable on the pivot to register with said scales.

4. A device of the character ,described comprising n' a t'op -member vwith opposite windows and having a pivot about which are scribed angular east and west scales at the outer edges of the windows, -a transparent course index member on the pivot and below the windows, and having diametrically opposite radial indices' to be set at respectlve scales at the windows, and a compass card turnable on the pivot to register with said scales.

In testimon whereof, I have hereunto set my hand at' an Francisco, California, this 26th day of July, 1919.

` FRED M. KRAMER.

In presence of- C. S. EVANS. l

lll 

